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Prediction of progression of interstitial lung disease in patients with systemic sclerosis: the SPAR model
  1. Wanlong Wu1,2,
  2. Suzana Jordan1,
  3. Mike Oliver Becker1,
  4. Rucsandra Dobrota1,
  5. Britta Maurer1,
  6. Håvard Fretheim3,
  7. Shuang Ye2,
  8. Elise Siegert4,
  9. Yannick Allanore5,
  10. Anna-Maria Hoffmann-Vold3,
  11. Oliver Distler1
  1. 1 Department of Rheumatology, University Hospital Zurich, Zurich, Switzerland
  2. 2 Department of Rheumatology, South Campus, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
  3. 3 Department of Rheumatology, Rikshospitalet, Oslo University Hospital, Oslo, Norway
  4. 4 Department of Rheumatology and Clinical Immunology, Charité University Hospital Berlin, Berlin, Germany
  5. 5 Rheumatology A Department, Cochin Hospital, Paris Descartes University, Paris, France
  1. Correspondence to Dr Oliver Distler, Department of Rheumatology, University Hospital Zurich, Zürich 8091, Switzerland; oliver.distler{at}


Objectives To identify the predictive clinical characteristics and establish a prediction model for the progression of mild interstitial lung disease (ILD) in patients with systemic sclerosis (SSc).

Methods Patients with SSc from two independent prospective cohorts were included in this observational study. All patients fulfilled the 2013 American College of Rheumatology/European League Against Rheumatism criteria, had mild ILD at baseline diagnosed by High-Resolution Computed Tomography (HRCT), available baseline and ≥1 annual follow-up pulmonary function tests and no concomitant pulmonary hypertension or airflow obstruction. ILD progression was defined as a relative decrease in forced vital capacity (FVC)%≥15%, or FVC%≥10% combined with diffusing capacity for carbon monoxide %≥15% at 1-year follow-up. Candidate predictors for multivariate logistic regression were selected by expert opinion based on clinical significance. A prediction model for ILD progression was established in the derivation cohort and validated in the multinational validation cohort.

Results A total of 25/98 and 25/117 patients with SSc showed ILD progression in the derivation cohort and the validation cohort, respectively. Lower SpO2 after 6 min walk test (6MWT) and arthritis ever were identified as independent predictors for ILD progression in both cohorts. The optimal cut-off value of SpO2 after 6MWT for predicting ILD progression was determined as 94% by receiver operating characteristic curve analysis. The derived SPAR model combining both predictors (SPO2 and ARthritis) increased the prediction rate from 25.5% to 91.7% with an area under the curve (95% CI) of 0.83 (0.73 to 0.93).

Conclusions The evidence-based SPAR prediction model developed in our study might be helpful for the risk stratification of patients with mild SSc-ILD in clinical practice and cohort enrichment for future clinical trial design.

  • systemic sclerosis
  • pulmonary fibrosis
  • arthritis

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  • Handling editor Josef S Smolen

  • Contributors Study conception and design: OD, WW, SJ, A-MH-V, YA, ES, SY, BM, RD, MOB. Acquisition of data: WW, OD, SJ, A-MH-V, HF, YA, ES. Analysis and interpretation of data: WW, OD, SJ. Drafting the article: WW, OD, SJ. Revising the article: A-MH-V, YA, SY, ES, HF, MOB, BM, RD. All authors have finally approved the submitted version to be published.

  • Funding This study was supported by a grant from Boehringer Ingelheim.

  • Competing interests OD has consultancy relationship and/or has received research funding from Actelion, Bayer, Boehringer Ingelheim, ChemomAb, espeRare foundation, Genentech/Roche, GSK, Inventiva, Italfarmaco, Lilly, Medac, MedImmune, Mitsubishi Tanabe Pharma, Novartis, Pfizer, Sanofi, Sinoxa and UCB in the area of potential treatments of scleroderma and its complications, and a patent mir-29 for the treatment of systemic sclerosis licensed. YA has received grants from BMS, Genentech-Roche, Inventiva, Sanofi and consulting fees from Actelion, Bayer, Biogen, Boehringer, Genentech-Roche, Galapagos, Inventiva, Medac, Pfizer, Sanofi and Servier, about the treatment of systemic sclerosis. BM has received research funding in the area of systemic sclerosis and related conditions from AbbVie, Protagen, EMDO, Novartis, German SSc Society, Pfizer, Roche, Actelion, MSD, OPO Foundation and a patent mir-29 for the treatment of systemic sclerosis licensed. WW, SJ, MOB, RD, HF, SY, ES and A-MH-V have nothing to disclose.

  • Patient consent Obtained.

  • Ethics approval Each participating centre has obtained approval from the local ethics committee for including a patient’s data in the SSc cohort after the patient has given written informed consent.

  • Provenance and peer review Not commissioned; externally peer reviewed.